Malicious PDF — malware analysis report

Static analysis result for SHA-256 5fd2052b0fb580b9…

MALICIOUS

PDF

3.4 KB First seen: 2026-05-10
MD5: 7577d3e23dc229dc5d002dd45adcc57c SHA-1: b2a124fe479d39fef175bce739bbf245c5fd642a SHA-256: 5fd2052b0fb580b9947d67a63e620313e806f34de5c718eeb38f8a156fe83bd9
118 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF sample contains JavaScript actions and uses obfuscated JavaScript rebuilding a char-code builder, indicating an attempt to execute arbitrary code. The use of ASCIIHexDecode with exploit indicators further suggests a vulnerability is being leveraged. The critical heuristic firing confirms the presence of malicious JavaScript designed to execute a payload.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 3

  • JavaScript action low 1 related finding PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • PDF JavaScript rebuilds a builtin via replace() to run a char-code array critical PDF_JS_REPLACE_OBFUSCATED_CHARCODE_BUILDER
    Decoded PDF JavaScript resolves a String builtin from a junked literal — e.g. String['eQvoaol3'.replace(/[3oQS5]/g,'')] yielding fromCharCode/eval — and feeds a large numeric char-code array through it to rebuild and execute the next stage. Dynamically reconstructing a builtin name by stripping junk characters has no benign purpose; paired with the char-code payload array it is an unambiguous obfuscated-JavaScript exploit dropper.
  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes